Pablo Gargallo was an early pioneer of avant-garde sculpture, cutting figures from sheet metal and being interested in tribal art which influenced his unique style. Julio Gonzalez was a skilled blacksmith who established iron sculpture as a new art form, using rods and surfaces to represent volume and penetrate figure and space. Alexander Calder was known for his delicate wire sculptures, from toy-like mobiles to large-scale kinetic sculptures using color and movement. Alberto Giacometti engaged with surrealism in his work from the 1930s onward, producing elongated and slim figures to accurately depict the human form from a distance in space through perspective and scale.